Crop water stress index for potato under furrow and drip irrigation systems

Summary This study was conducted to determine the crop water stress index (CWSI) for potato (Solanum tuberosum L.) grown under furrow and drip irrigation methods and subjected to three different irrigation levels (100, 50 and 0% replenishment of soil water depleted). The lower (non-stressed) and upper (stressed) baselines were determined empirically from measurements of canopy temperatures, ambient air temperatures and vapor pressure deficit values. Tuber yield decreased when mean CWSI prior to irrigation exceeded 0.68 in furrow and 0.81 in drip irrigation. The tuber yield was directly correlated with the seasonal CWSI values and the linear equations for furrow and drip irrigation methods, Y = −45.82 CWSI + 50.69 and Y = −52.65 CWSI + 58.44, respectively, can be used for yield prediction.     

Application of infrared thermography to assess cassava physiology under water deficit condition

ABSTRACT

Water deficit stress is a major factor that inhibits the overall growth and development in cassava (Manihot esculenta), leading to decreased storage root yield. We conducted a study to investigate whether thermal sensing could be used to indicate water deficit stress and the health and yield of cassava crops in field. The objective of the study was to use thermal imaging to determine relationship between crop water stress index (CWSI) and physiological changes, and to identify the critical CWSI point in fields of cassava cv. Rayong 9 under well-irrigated and water-deficit conditions. At the time of storage root initiation (85 DAP [day after planting]), thermal imagery was collected and the physiological changes and growth characters were measured prior to storage root harvesting (162 DAP). Thermal infrared imager was used to measure the canopy temperature and CWSI of cassava plants. Net photosynthetic rate (P_n), stomatal conductance (g_s) and transpiration rates (T_r) of cassava plants under water deficit conditions for 29 d (114 DAP) were significantly decreased, leading to delayed plant growth as compared to those under well-irrigated conditions. In contrast, air vapor pressure deficit (VPD_air) and CWSI in drought-stressed plants were higher than well irrigated plants. High correlations between T_r/g_s/P_n and CWSI were observed. The study concludes that CWSI is a sensitive indicator of water deficit stress caused due to stomatal function.

Abbreviations: CWSI: crop water stress index; DAP: day after planting; Pn: net photosynthetic rate; gs: stomatal conductance; Tr: transpiration rate; VPDair: air vapor pressure; RMSE: root mean square error     

Evaluation of on-farm irrigation scheduling methods for potatoes

The neutron probe, infrared thermometry and crop water stress index (CWSI), and a computer-assisted irrigation scheduling method were evaluated in terms of their effect on tuber yield, tuber quality, and water use. The experiment was conducted during 1990 and 1991 near Othello, central Washington, using Russet Burbank potatoes grown in a silt loam soil. Irrigation treatments did not commence until after tuber initiation. In general, no differences in total number of tubers and total tuber yield resulted from the different scheduling methods. However, the canopy temperature method showed reduction in the yield of number one tubers in 1990. The least total irrigation water was applied during the growing season with the neutron probe method. Using CWSI values above 0.5 to 1.0 (scale 0 to 10) for two consecutive days as a threshold to schedule irrigations appeared to be adequate for potatoes grown in silt loam soils. However, shortcomings of infrared thermometry suggested that this method may not be practical for scheduling irrigation of potatoes.     

Relationship between foliage temperature and water stress in potatoes

Field studies were conducted in southern Idaho to evaluate the possibility of using thermal infrared measurements of potato foliage to detect soil water deficits. Concurrent measurements of foliage-air temperature differences (T_f-T_a), leaf water potential (gy_leaf) and vapor pressure deficit (VPD) were obtained from differentially-irrigated Russet Burbank and Kennebec potatoes during the 1982 and 1983 growing seasons. Foliageair temperature differences for well-watered potatoes were linearly related to VPD. Differences in T_f-T_a values between stressed and well-watered potatoes were relatively small in the early morning when evaporative demand was low. However, severe soil water deficits caused afternoon T_f-T_a values to rise as much as 8.0 C above non-stressed levels under conditions of high VPD. Foliage-air temperature differences and VPD data were used to construct a plant water stress index (PWSI) which reflected the rise in T_f-T_a above non-stressed levels at a given VPD. The PWSI was linearly related to depressions in gy_leaf caused by moderate to severe soil water deficits. However, the PWSI did not increase significantly above non-stressed values unless the soil matric potential gy_soil fell below -70 kPa (centibars). Since potatoes are normally irrigated before gy_soil falls below ?60 kPa, it appears that foliage temperature measurements cannot be used to effectively schedule irrigation for this crop.     

Influence of ethylene on black spot of potato tubers

Sound, hand harvested, whole potatoes were exposed to continuous flowing atmosphere containing air, air with 3 or 5% CO₂, and air with concentrations of 0.5, 1.0, and 10ppm C₂H₄ for periods of 1 to 11 days at 20°C. At 1-day intervals, potatoes were bruised and black spot development assessed. Development of black spot in potatoes exposed to C₂H₄ was equal to or less than in potatoes at harvest. The severity remained low during 3-day exposure to 1 ppm C₂H₄ and after transfer to 4 days in air, then increased. Severity of black spot increased in potatoes exposed to air, with intermediate response from exposure to air with CO₂. With an increase in sprouting, differences in black spot among treatments diminished. Less black spot developed in immature than in mature potatoes.     

Rates of internal blackspot bruise development in potato tubers under conditions of elevated temperatures and gas pressures

Internal blackspot bruising was produced in Russet Burbank tubers by dropping a 150 g weight 40 cm through a slotted guide tube and incubating the tubers for varying time periods at temperatures ranging from 10 to 80 C. When potatoes were bruised following 1 to 5 months storage, those tubers incubated at 10 C required 48 hr for maximum blackspot development. Increasing the incubation temperature accelerated blackspot formation with an optimum response at 36 to 40 C. At 40 C tubers reached maximum discoloration within 6 hr. Bruised tubers were also exposed to combinations of varied temperatures and varied gas pressures of 0.3 to 2.1 kg/cm² using air, O₂, CO₂, and N₂. Pressurized air slightly enhanced the temperature effect at 40 C; pressurized O₂ had no significant effect upon blackspot development, while CO₂ and N₂ inhibited blackspot formation. Blackspot bruises incurred in the field during harvest required a longer incubation period at a lower temperature than did bruises inflicted on tubers held in storage for 1 to 5 months.     

Estimation of critical nutrient range of petiole nitrate for sprinkler-irrigated potatoes

The relationship of yield to concentration of NO₃ in petioles of potatoes (Solanum tuberosum L.) was studied as part of a comprehensive project on N use efficiency. The objective of this study was to estimate the critical nutrient range (CNR) of petiole NO₃ for Russet Burbank potatoes treated with N supplements during the season. Treatments totaled 224, 336, and 560 kg N ha^-1 for the season as NH₄NO₃ on this low N soil with one-third to one-half of the N applied at planting and the rest as periodical supplements during the season. Average yield of potatoes (74 Mt ha^-1) was highest with 336 kg N ha^-1. From this it was assumed that 224 N was optimum. Petiole NO₃ decreased through the season with linear regressions of petiole NO₃ versus time for each of three N rates accounting for variation in petiole NO₃. It was concluded that at the start of the season, the estimated CNR for petiole NO₃-N of potatoes was within the range from 9 to 13 g kg^-1. Numerically, CNR values decrease with time as the season progresses. It is concluded that until more precise calibrations are made available, the CNR approach with petiole NO₃ will be more helpful in cross checking the nutritional status of potatoes fertilized periodically with N supplements than in serving as a primary fertilizer guide.     

Stomatal behavior of potatoes under nonlimiting soil water conditions

Field studies were conducted to examine the relative effects of net irradiance (R_n), air vapor pressure deficit (VPD) and leaf water potential (Ψ₁), on leaf conductance, (C₁) of well-watered potatoes. Conductances of sunlit, surface-layer leaves for the cultivars Russet Burbank, Kennebec and Lemhi Russet were positively correlated with R_n (r²=0.79, 0.83 and 0.62, respectively) for R_n between 100 and 650 Wm^-2. Leaf conductance (cm s^-1) for all three cultivars was described by the linear relation: C₁=0.871 +0.0028 R_n (r²=0.73). Mean C¹ for a full Russet Burbank canopy, comprised of measurements from both sunlit and shaded leaves, was also linearly related to R_n. Although VPD and Ψ₁ were significantly correlated with C₁ (r²=0.44 and 0.46, respectively), the results of multiple regression analysis showed that they had no additional effect on C¹ beyond that attributed to R_n. These results indicate that potato leaf conductance is primarily related to irradiance under nonlimiting soil water conditions.     

Effect of Cooking and Processing on CIPC Residue Concentrations in Potatoes and Processed Potato Products

Residue concentrations of the sprout suppressant chlorpropham (or CIPC) were determined in raw and cooked potatoes and processed potato products, 48 h after CIPC aerosol treatment and after 30 days of subsequent storage at 4 or 12 °C. In the raw (uncooked) tuber, 48 h after CIPC treatment, the CIPC residue in the peel was 4.7 mg kg^-1, while in the peeled tuber it was 0.1 mg kg^-1. Boiling resulted in a decrease in residue concentration in the peel, but no significant differences in the residue concentration of the peeled tuber were observed. Pressure cooking resulted in a significantly increased residue concentration in the peel, but no significant change in the peeled tuber, whereas microwave cooking also did not increase the residue concentration in the peel significantly compared with that in raw tubers. Also the trend towards increases in residue concentration in microwave-cooked peeled tubers was not significant. The CIPC residue concentration detected in peeled tubers was 0.4–0.7 mg kg^-1 after boiling, 0.4–1.5 mg kg^-1 after pressure cooking and 0.4–3.8 mg kg^-1 after microwave cooking. The highest values were always found for tubers stored for 30 days at 4 °C. Processed products such as crisps, French fries, dehydrated sliced potatoes and starch contained different concentrations of CIPC residue, which was also detected in the cooking water and frying oil. The highest residue concentrations detected were 0.7, 4.7, 1.3 and 0.2 mg kg^-1 in crisps, French fries, dehydrated sliced potatoes and starch, respectively. The highest CIPC residue concentration observed in raw potatoes was much lower than the maximum residue level of 10 mg kg^-1 prescribed by the European Union.     

Eclipse Effects on CO2 Profile within and above Sorghum Canopy

Abstract

We analyzed the effects of a partial solar eclipse (22 July 2009) on microclimate including vertical gradients of CO₂ concentrations ([CO₂]), so called [CO₂] profile, in a mature sorghum canopy. Together with CO₂ measurement, major photosynthetic drivers of microclimate, light intensity, temperature and atmospheric H₂O concentration ([H₂O]) were also measured simultaneously at the same place and height. [CO₂] at 6.0, 3.2, 2.1, 1.4, 0.7, 0 m above the ground (canopy height was 3.2 m) increased by 5.8, 4.8, 9.0, 7.8, 6.4, 7.6μmol mol-¹, respectively, from 1 hour before the eclipse maximum to the eclipse maximum, during which theincident solar radiation above the canopy dropped by 1473 μmol photons m-² s-¹. However, it declined by 3.4, 10.6, 10.8, 6.0, 5.4, and 5.8μmol mol-¹, respectively, from the eclipse to 1 hour later,during which the incident radiation increased by 1350μmol photons m-² s-¹. The [CO₂] profile during the eclipse was uniform except for higher [CO₂] near the ground. Comparative analysis of theeffect of light intensity on the microclimate during the eclipse-induced light decreasing phase (ELDP) and eclipse-induced light increasing phase (ELIP) revealed that [CO₂], [H₂O], temperature and relative humidity (RH) are significantly correlated with the light intensity above the canopy in a nearly linear fashion. Furthermore it indicated that detected less light-reacted canopy photosynthesis at a higher layer within the canopy during ELIP might be due to slower response of stomatal opening (than closing) to the light intensity above the canopy.     

Effect of high water temperature during vegetative growth on rice growth and yield under a cool climate

Global warming is likely to increase spring temperatures in regions with a cool climate. To examine the effects of this change on rice productivity, we exposed rice plants to a higher (by +2.7 to +2.8 °C) water temperature (T_w) during the vegetative growth period (for 35-50 days) under three levels of N fertilization. High T_w during vegetative growth made the heading stage occur 4-7 days earlier for all levels of N fertilization in both years. The crop growth rate during the treatment period was greatly enhanced by high T_w: by 51-82% in 2008 and by 49-62% in 2009. There was no T_w × N fertilizer interaction. This increased growth was associated with increased leaf expansion and increased canopy radiation capture rather than with increased radiation-use efficiency. However, the positive effect decreased during subsequent growth stages under all levels of N fertilization, leading to no significant differences in total biomass at maturity. High T_w during vegetative growth greatly reduced SPAD values during the grain-filling stage compared with SPAD values in the control T_w treatment, for all levels of N fertilization, and decreased leaf photosynthesis during the mid-grain filling stage. Grain yield was not significantly affected by high T_w at any N fertilizer level or in either year.     

Carbon dioxide enrichment and temperature effects on cotton canopy photosynthesis,transpiration, and water-use efficiency

The objectives of this study were to evaluate effects of ambient and double ambient [CO₂] at a range of growing temperatures on photosynthesis, respiration, transpiration, water-use efficiency and dry matter accumulation of cotton plants (Gossypium hirsutum L., cv. DPL 50). In Experiment I, plants were grown outdoors until first bloom, then transferred into naturally lit growth chambers and grown for 22 days at 30/18°C with five CO₂ concentrations varying from 350 to 900 μl l⁻¹. In Experiment II, air temperatures were maintained at 20/12, 25/17, 30/22, and 35/27°C day/night during a 70-day experimental period with [CO₂] of 350 and 700 μl l⁻¹ at each temperature. Photosynthesis increased with [CO₂] from 350 to 700 μl l⁻¹ and with temperature. Plants grown at 35/27°C produced fewer bolls due to abscission compared with plants grown at optimum temperatures (30/20°C). At higher [CO₂], water-use efficiency increased at all temperatures due mainly to increased canopy photosynthesis but also to more limited extent to reduced canopy transpiration. Increased photosynthesis at higher [CO₂] resulted in greater dry matter accumulation at all temperatures except at 20/12°C. Respiration increased as dry matter and temperature increased. Plants grown at higher [CO₂] had less respiration per unit dry matter but more per unit area. These results indicate that future increases in [CO₂] are likely to benefit cotton production by increasing carbon assimilation under temperatures favorable for cotton growth. Reduced fruit weights at higher temperatures indicate potential negative effects on production if air temperatures increase as projected in a high-CO₂ world.     

Effect of controlled atmosphere,temperature and cultivar on sprouting and processing quality of stored potatoes

Summary Three crisping potato cultivars, Record, Saturna and Hermes, were stored at 5 or 10°C in gas mixtures of either 0.5% CO₂ and 21.0% O₂ (control) or 9.4, 6.4, 3.6 or 0.4% CO₂ all combined with 3.6% O₂. There was almost complete sprout inhibition, low weight loss and maintenance of a healthy skin for all cultivars stored in 9.4% CO₂ with 3.6% O₂ at 5°C for 25 weeks. When tubers from this treatment were stored for a further 20 weeks in air at 5°C the skin remained healthy and they did not sprout. The fry colour of crisps made from these potatoes was darker than the industry standard but when they were reconditioned, tubers of cv. Saturna produced crisps of an acceptable fry colour while crisps from the other two cultivars remained too dark. Reducing sugar levels were related to fry colour both after storage and after reconditioning. The other gas combinations and the controls did not have the same effect on sprouting and none of the controlled atmosphere treatments controlled sprouting at 10°C.     

A System for the Measurement of Vertical Gradients of CO2, H2O and Air Temperature within and above the Canopy of Plant

Absract

This technical report describes a gradient system for characterizing the vertical gradients of CO₂, H₂O, and air temperature within and above the canopy of plants. The system is low in cost and easy to use. The instruments were fitted and placed in one box with a total weight of about 10 kg. The box can be carried and moved from one site to another. The features of this apparatus are high frequency sampling cycle as short as 1 min per cycle for all six measurement levels and fast response gas analyzer for measurement as short as 10s per level. Two exhaust pumps, one sampling pump, six 3-way solenoid valves, and flow meter were used to insure simultaneous flow rate of air in all tubes from all measurement levels. This system transfers data from the data-logger directly to the add-in Spreadsheet of Microsoft Excel by using an Ethernet cable to automatically convert digital data to scientific units in less time. This system also allows the use of multiple micro-environmental sensors that can be sampled at the same time. It is useful not only for agricultural ecosystems but is also adequately sensitive and rapidly responds to the gas analyzer with a modifiable flow rate meter for use in forest ecosystems. This system also has potential for use in the measurement of CO₂, H₂O, associated environmental elements, and CO₂ storage flux within the canopy of plant, and other processes including a CO₂ sink and source.     

Soil solution levels of nitrate nitrogen in a potato-buckwheat rotation

Using excessive rates of N fertilizer on potatoes in Maine has been a common practice. Excessive N did not significantly increase potato yields above the recommended N application. The impact of N fertilization upon soil solution levels of NO₃ ^-N in the B and C soil horizons was compared at three application levels of N. High N resulted in greater levels of NO₃ ^-N in the C horizon and the strong possibility of groundwater contamination. There was no apparent change in the NO₃ ^-N content of the C horizon during the winter following buckwheat, but there was an increase of NO₃ ^-N in this horizon when fall levels beneath potatoes were compared to spring values under buckwheat. After one year of no N application soil solution NO₃ ^-N levels in the B horizon returned to amounts that were the same as those receiving no N fertilization for a decade.     

海南岛西部橡胶人工林冠层温度变化及其与微气象要素的关系

冠层温度是表征植物生理生态过程及能量平衡状况的重要参数之一。为探讨热带森林冠层温度在不同时间尺度下的变化规律并且初步分析环境因素与冠层温度的关系,本研究利用红外温度传感器测定了海南岛西部橡胶人工林2017年全年的冠层温度数据以及同步得到的冠层微气象资料,对干季和湿季下海南岛西部橡胶人工林冠层温度（T_c）与大气温度（T_a）特征进行了分析,同时结合微气象因子进行了讨论。结果表明：橡胶人工林冠层温度全年各月日变化都为单峰曲线,相比T_a,T_c具有明显的位相前移、变化加剧的特点。白天林冠边界层处于不稳定状态,林冠为土壤-植物-大气连续体（Soil-Plant-Atmosphere Continuum,SPAC）的热源;夜晚林冠边界层为逆温层结,呈稳定状态,林冠为SPAC的冷源。湿季冠层温度高于干季。若仅考虑T_a,T_c与T_a之间具有很好的线性关系,其线性方程为T_c= 1.033T_a-0.656;若同时考虑大气温度（T_a）、净辐射（R_n）、相对湿度（RH）与风速（V）等微气象因子,其复相关系数表明全年均呈极显著相关,偏相关系数表明干季冠层温度变化主要受T_a、R_n和RH的影响,其次受V的影响;湿季主要受T_a与RH的共同作用,R_n与V对其的影响相比可忽略不计。此研究结果初步揭示了橡胶人工林冠层温度的全年变化规律及其与众多微气象因子之间的关系,为进一步探究冠层温度变化及其影响机制提供科学依据。     

温敏核不育水稻植株温度的变化规律及与环境关系的模型

以温敏核不育水稻培矮64S为材料,采用10～15 cm水层灌溉处理和无水层对照,对植株温度及其与植株冠层小气候和灌溉水因子的关系作了分析。水稻植株温度与150 cm大气温度在数值和相位上均存在一定差异。8:00～20:00植株温度均明显低于大气温度,21:00～次日7:00植株温度与大气温度基本相同;日最高植株温度出现在13:00,比最高大气温度提前1 h,但日最低植株温度和最低大气温度均出现在6:00;植株温度的平均日较差比气温小。在同一高度上相比,晴天6:00～13:00植株温度比空气温度高,而且提前1 h升温,18:00～次日6:00则两者逐渐趋同或植株温度稍低;而在阴天,植株温度则全天一直高于空气温度,最高温度出现的时间也相同。植株温度白天的变化主要受太阳辐射的影响,天空状况（云量或日照时数）和风速都通过对辐射强度的调节和热量的交换而产生作用。植株温度夜间的变化主要受灌溉水的影响。在本试验条件下,日平均气温（Ta）29.6℃是灌溉水提高或降低植株温度的临界温度值,当Ta＞29.6℃时,灌溉水具有降低植株温度的作用,反之,灌溉水具有提高植株温度的作用。植株温度与水 气温差符合二次曲线关系。植株冠层在白天吸收或反射太阳辐射,夜间则阻挡热量散失,对调节植株温度具有明显的缓冲效应。通过相关分析和回归拟合,建立了两个可供实用的水稻植株温度的环境模型。     

Cool Farm Tool – Potato: Model Description and Performance of Four Production Systems

The Cool Farm Tool – Potato (CFT-Potato) is a spreadsheet programme that allows the calculation of the amount of CO₂ equivalents that it costs to produce 1 t of potato. The spreadsheet was adapted from an original generic version of the tool, and completed for potato production in diverse production areas in the world applying different levels of technology. The CO₂ embedded in chemicals during their production and released from the soil after nitrogen fertilization in the CFT-Potato has been updated to consider more recent products and production methods. Energy costs of the operations in the original version taken from generic data provided by the American Society of Agricultural and Biological Engineers Standard, however, were altered (usually increased) where there was evidence from practical sources that the original figures did not apply. For example, the figure of around 16 l of diesel per ha for potato harvesting in the original version was corrected to 60 l of diesel per ha based on observational data. Figures for typical potato operations such as windrowing were supplied. Irrigation with pumps powered by diesel or electricity from the grid, with a centre pivot, a rain gun, drip irrigation and flooding and energy cost for extracting water from deeper sources were also added. We added data for grading, washing, store loading and unloading, the application of a sprout suppressant and storage with ventilation of ambient air or forced refrigeration. The CFT-Potato can be used by growers to calculate the actual costs of 1 t of potato in terms of kilograms CO₂ and explore the repercussion of altered management options. Here the comparison of four potato production systems in the Netherlands is shown: seed potatoes (115 kg CO₂/t), table potatoes (77 kg CO₂/t), starch potatoes (71 kg CO₂/t) and organic potato (82 kg CO₂/t). Based on potato dry matter, however, starch potato has the lowest footprint mainly due to the extensive use of pig slurry of which the production and transport CO₂ costs are attributed to the pig production chain.     

Weight loss of potatoes as affected by age,temperature, relative humidity and air velocity

The factors affecting potato tuber weight loss were studied by suspending individual tubers of Kennebec, Red Pontiac, and Norgold Russet potatoes in chambers where temperature, relative humidity, and air flow past the tubers could be controlled. The results of a regression analysis indicated that the age of the tubers closely followed by temperature was most highly correlated to weight loss. Tuber weight and relative humidity were next and about equally correlated with weight loss. Air velocity had the lowest correlation coefficient Prediction equations for predicting the weight loss of the potato tubers as a function of the various environmental and potato tuber variables were developed from a step-wise regression analysis program. The standard error for these regression equations was about ±1.5% weight loss from the predicted value The weight loss of the tubers in this experiment are likely higher than bulk stored potatoes because of the greater surface area exposed to air flow. Also, other than temperature, the other variables (air velocity, relative humidity, and potato weight) were relatively uncontrolled and therefore had high variations. A plot of weight loss versus time indicates a non-linear response with greater variation as time increases.     

Effect of method of irrigation on the total glycoalkaloid and nitrate-nitrogen content of Rosa potatoes

The effect of two irrigation methods, microjet mist and impact sprinkler, on the total glycoalkaloid (TGA) and nitrate-nitrogen (NO_3?N) content ofSolanum tuberosum L. cv. Rosa was investigated. Potatoes irrigated by microjet mist were significantly higher in TGA and lower in NO_3?N content than control potatoes receiving no irrigation. The impact sprinkler method produced potatoes significantly higher in NO_3?N than controls. The TGA content of potatoes irrigated by the sprinkler method was not significantly different from controls. Mist-irrigated potatoes were higher in TGA and lower in NO_3?N content than sprinkler-irrigated potatoes.